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<html lang="en">
  <head>
    <meta charset="UTF-8" />
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    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
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  <body>
    <script>
      // 输入：[1, 2, 3, 4],  10
      // 输出：[1, 2, 3, 4, 10]
      let item = 10;
    
      var arr = [1, 2, 3, 4, 5];
      function append(arr, item) {
        arr.splice(arr.length, 0, item);
        console.log(arr);
      }
      append(arr, item);
    </script>
  </body>
</html>
